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We thank Dr. Juan Jose Segura
Fonseca, Hospital San Juan de Dios, Costa Rica, for contributing this case. We
invite you to contribute a Case of the Week by sending an email to NPernick@PathologyOutlines.comwith microscopic images (any size, we will shrink if necessary) in
JPG or GIF format, a short clinical history, your diagnosis and any other
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Please only send cases with a definitive diagnosis.

Case of the Week #49

Clinical history

A 68 year old woman was seen in the
outpatient clinic because of difficulty in swallowing and sensation of a
"large foreign body" in her throat, of several months duration. On
physical examination, a large, solid, pale yellow tumor was located in the soft
palate. Complete resection of a large lipoma-like tumor mass was performed.

Microscopic
findings: On
low power (figure 3),
a tumor characterized by peripheral lipomatous tissue and central salivary
gland elements with prominent dilation of ducts is seen. In the periphery,
there is a predominance of adipose tissue that looks like a lipoma (figure 4).
In the central area, there is a mixture of adipose tissue, fibrous trabeculae
and numerous salivary gland acini. Some dilated ducts are also seen (figure 5).
Other areas show acinar predominance and numerous ectatic ducts lined by flat
cuboidal epithelium (figure 6).
Numerous dilated ducts are arranged in a lobular-like structure with prominent
fibrosis (figure 7).

Focally, there is marked dilatation
of ducts with prominent fibrosis of the wall infiltrated by nodular aggregates
of lymphocytes, resembling small lymphoepithelial cysts (figure 8,
figure
9)

What is your diagnosis?

(scroll down to
continue)

Diagnosis:

Sialolipoma of the
soft palate

Discussion
(written by contributor)

Intraoral lipoma is a well-known
entity (1, 2) but lipomatous tumors including salivary gland tissue containing
clustered or peripherally located ducts in acinar glandular tissue are
uncommon. Under the designation of sialolipoma, Nagao et. al. from Japan described a new variant of salivary gland lipomatous tumor (3). They reported seven
cases, five men and two women, aged 20-75 years old. Five tumors were located
in the parotid gland, one in the hard palate and one in the soft palate.

Grossly, the tumors were well
circumscribed and resembled an ordinary lipoma. Histologically, they were
characterized by a proliferation of mature adipose tissue intermingled with
acinar, ductal, basal and myoepithelial cells of normal salivary gland. Duct
ectasia with fibrosis and prominent lymphoid infiltrates with nodular
aggregates in the stroma is a constant finding.

These tumors have benign behavior. No
recurrences have been noted, including from recent reports in the floor of the
mouth (4) or the parotid gland (5).

This Case corresponds to the fourth reported case of sialolipoma located in the
oral cavity and the second in the soft palate.